Tank Overturning/Stability
Tank Overturning/Stability
(OP)
Hello all,
With regards to the 3 uplift criteria in section 5.11.2.1 ( API 650 12th Edition Addendum 2 ).
For the value of MDL is it acceptable to include the weight of the shell insulation if the tank is lagged?
Similarly can we also include the weight of any roof insulation in the value for MDLR?
Thanks in advance for your thoughts.
With regards to the 3 uplift criteria in section 5.11.2.1 ( API 650 12th Edition Addendum 2 ).
For the value of MDL is it acceptable to include the weight of the shell insulation if the tank is lagged?
Similarly can we also include the weight of any roof insulation in the value for MDLR?
Thanks in advance for your thoughts.





RE: Tank Overturning/Stability
RE: Tank Overturning/Stability
http://rfi.api.org/Index.aspx
RE: Tank Overturning/Stability
RE: Tank Overturning/Stability
My humblest of opinions only...
RE: Tank Overturning/Stability
I also prefer to take the more conservative approach and have the tank stable on its own merit and not be 'clutching at straws' so to speak...however i will send in a Tech Enquiry to API just out of interest...(thanks for the link to the enquiry form IFRs).
I will let you know of any outcome from API. How long do they typically take to respond?
RE: Tank Overturning/Stability
Any dead & removable weights like Insulation actually lowers the chance of Anchoring and its sizes/quantity.
RE: Tank Overturning/Stability
Again if the roof is insulated could this additional weight be included in the relevant Annex F formulas?
RE: Tank Overturning/Stability
On the technical inquiries, kind of a mixed record. Figure a few months, never quick enough to help with a particular tank, it's always for the next one. I've had one request rejected due to "not approving specific methods" or whatever, when in my judgment, it didn't fall in that category at all. I've had a couple of inquiries that apparently just disappeared- no response ever, on what seemed to me a perfectly reasonable question.
RE: Tank Overturning/Stability
RE: Tank Overturning/Stability
RE: Tank Overturning/Stability
It will be interesting to see what API come back with regarding my technical query under API 650 if it is actually allowed in API 620.
Will keep you posted on this either way!
RE: Tank Overturning/Stability
RE: Tank Overturning/Stability
The definition of MDLR as per API 650 "is the moment about the shell-to-bottom joint from the nominal weight of the roof plate plus any attached structural" states to use the nominal weight and any attached structure. As a general rule, what i think, whenever you are designing for wind, do design it for the most stringent condition, which is having the least weight. Whereas, when you are designing it for seismic, do consider the maximum weight in your calculations since, for seismic, this is stringent one.
Having said that, i would suggest you to "not consider" the weight of insulation in your calculations for anchorage check against wind loading. But, do include all the structures since they would increase the projected area of the wind.
Also, when you check the anchorage against seismic loading (Appendix E), do consider the weight of the attached insulation.
Regards,
Mech2325
RE: Tank Overturning/Stability
I will let you all know what answer API reply back with following the tech enquiry sent.